The invention relates generally to an off-highway vehicle and more specifically to an earth moving machine having a tractor section and a trailing section, with the tractor section having an axle assembly which is coupled to a transmission located at its front end and which has provision for relative vertical movement.
In Swanson U.S. Pat. No. 3,865,205 there is disclosed a tractor section having an engine at the rear and a transmission at the front with the transmission being coupled to the axle assembly by means of a drive shaft having a universal joint at its front end. The universal joint is transversely aligned with the axle assembly pivot connection so that as the wheels of the tractor section move upwardly and downwardly on irregular terrain the universal joint is rocked off center to an equal angular degree.
Moreover in the construction of the prior patent the tractor axle assembly has rolling rigidity with respect to the tractor section so that the tractor section and the driver who is seated thereon are subject to violent lateral swaying movement as the tractor wheels tilt from side to side in the following of irregular terrain. Where the tractor section has rolling rigidity with respect to the trailing section which, in turn, has rolling rigidity with respect to its supporting wheels, it is possible, on irregular terrain, for one of the tractor wheels to lose traction with respect to the ground.